CN101839803A - Low-laser loss parameter comprehensive measurement device for high reflector - Google Patents

Abstract

The invention relates to a comprehensive measuring device for low-loss parameters of a high-reflection mirror laser. In the process of developing a high-performance laser gyroscope, the high reflection mirror in the ring cavity is required to have very low scattering, transmission and backscattering losses. In the ring laser gyroscope, the loss generated by each component of the laser cavity is the cause of its lock-up important reason. The invention provides a comprehensive measurement device for low-loss laser parameters with a high reflection mirror, which includes a light source assembly and an integrating sphere arranged on an optical platform. A transmission measurement component A, an integral scatter measurement component B and a backscatter measurement component C are provided. The invention realizes the measurement of integral scattering rate, transmittance and backscattering rate on the same device, enhances the measurement function of the device, reduces the measurement cost, and can automatically change the incident angle by rotating the sample during measurement, and all three measurements can be obtained 2D distribution of measured values of a sample.

Description

High reflective mirror laser low loss parameter comprehensive measurement device

technical field

The invention belongs to the technical field of optical element testing, and in particular relates to a comprehensive measurement device for low-loss laser parameters of a high-reflection mirror.

Background technique

Low-loss high-reflection mirrors are widely used and play an important role in laser gyroscopes, high-power lasers and other laser systems. For example, a typical laser gyro system has a polygonal (commonly regular quadrilateral or triangular) optical resonator. The rate is as high as 99.99%. In the process of developing a high-performance laser gyroscope, the high reflection mirror in the ring cavity is required to have very low scattering, transmission and backscattering losses, because in the ring laser gyroscope, the loss generated by each component of the laser cavity is the cause of its lock-up important reason.

Accurately measuring low-loss parameters such as integrated scattering rate, transmittance, and backscattering rate of high-reflectors has important guiding significance for improving the precision and manufacturing quality of high-reflectors, and is an important technological means to guide the production of high-reflectors.

It can be seen from the literature review that there are few reports at home and abroad on the fully integrated scattering measurement of highly reflective mirrors (or ultra-smooth surfaces). The project team of this invention has searched domestic and foreign patent documents and published periodical papers, and has not found reports and documents closely related to or identical to the present invention.

Contents of the invention

 The present invention provides a comprehensive measurement device for low-loss laser parameters with high reflection mirrors, so as to fill in the gaps in this field in the prior art.

In order to solve the problems of the prior art, the technical solution provided by the invention is:

A high reflective mirror laser low-loss parameter comprehensive measurement device, including a light source assembly and an integrating sphere arranged on an optical platform. The difference is that: a transmission measurement component A, an integral scatter measurement component B and a backscatter measurement component C are also included;

The transmission measurement component A is arranged on the optical path of the incident light, including a transmission measurement frame and a transmission extinction trap, wherein the transmission extinction trap can adjust its position according to the angle of the incident light, and is arranged on the reflected light path to absorb the reflected light;

The backscatter measurement assembly B includes a backscatter aperture, a backscatter measurement frame and a backscatter extinction trap, and a backscatter entrance and a backscatter measurement port are arranged on the wall of the integrating sphere on the light path of the incident light passing through the center of the sphere, The backscatter aperture is set on the backscatter entrance, and a backscatter measurement frame is set outside the backscatter measurement port. The backscatter measurement frame can be rotated, and a backscatter extinction trap is set on the optical path of the reflected light;

The integral scatter measurement assembly C includes an integral scatter aperture, an integral scatter measurement frame and an integral scatter extinction trap, an integral scatter entrance and an integral scatter measurement port are arranged on the wall of the integrating sphere on the incident light path, and the integral scatter aperture is set On the integral scatter entrance, the integral scatter measurement frame is set on the integral scatter measurement port, and the integral scatter light outlet is set on the wall of the integrating sphere on the reflected light path between the integral scatter measurement port and the integral scatter extinction trap, and enters into the integrating sphere The optical path of the incident light of the integral scattering entrance and the reflected light reflected from the integrating sphere is approximately equal, and the incident angle is the measurement angle;

Accessories are provided on the incident port, the measurement port and the light exit port, and the accessories are standard whiteboards.

An adjustable optical path turning device is arranged between the above-mentioned transmission measurement component A and the integrating sphere.

The above optical path turning device includes a movable third reflective mirror and a fourth reflective mirror which are arranged oppositely.

There are multiple wave plates mentioned above, which are respectively arranged on the rotatable wave plate fixed disk, and the above-mentioned attenuation plates are provided in multiples, which are respectively arranged on the rotatable attenuator fixed disk.

There are four holes symmetrically distributed at 90° and the centers are located on the same circle on the above-mentioned wave plate fixed disc, three of which are respectively equipped with two 1/2 wave plates and one 1/4 wave plate, and the other is Through holes; the fixed disk of the attenuation plate is provided with four holes symmetrically distributed at 90° and the centers are located on the same circumference, relative to the position of the 1/2 wave plate and the 1/4 wave plate on the fixed disk of the wave plate The ones set are 1%, 0.1%, and 0.01% light attenuating sheets, and the other is a through hole.

The above-mentioned transmission measurement frame, integral measurement frame and backscatter measurement frame are all composed of an electric control turntable and an electric control x-y translation stage, and a fixed ring is arranged on the translation stage. The fixing ring is used to install the sample to be measured.

Technical effect of the present invention:

The invention has flexible design, realizes the measurement of integral scattering rate, transmittance and backscattering rate on the same device, enhances the measurement function of the device, and reduces the measurement cost. The present invention can not only measure the integrated scattering rate of the high reflection mirror (sample), but also measure the transmittance of the low transmittance sample, and can also measure the backscattering rate of the high reflection mirror (sample), and the measurement can be performed automatically by rotating the sample By changing the incident angle, the two-dimensional measured value distribution map of the sample can be obtained for the three measurements.

High reflection mirror multi-point multi-track integral scattering rate test: test range: 10~1000ppm, light incident angle 45°; same point test repeatability: 10~100ppm, test repeatability ± 1ppm; 100~1000ppm, test repeatability ± 5ppm;

Mirror multi-point multi-track transmittance test: test range 60ppm~0.5%; test sample angle 0~90° adjustable; same point test repeatability ± 10ppm;

High reflection mirror multi-point multi-track backscattering rate test: test range: 10~1000ppm, light incident angle 30~45° adjustable; same point test repeatability: 10~100ppm, test repeatability ± 1ppm; 100~1000ppm, test repeatability Sex ±5ppm;

Incident light polarization state: s-, p-linearly polarized light, circularly polarized light.

Description of drawings

Fig. 1 is a schematic diagram of the installation structure of the present invention.

The reference signs are explained as follows:

1-Laser source, 2-Polarizer, 3-Optical modulator, 4-Wave plate, 5-First reflector, 6-Attenuation plate, 7-Beam shaping component, 8-Second reflector, 9-Transmission Measuring frame, 10-transmission extinction trap, 11-third reflector, 12-fourth reflector, 13-backscatter aperture, 14-integral scattering aperture, 15-integrating sphere, 16-integral scattering light outlet, 17 -Measured sample, 18-backscatter measurement port, 19-backscatter measurement sample, 20-photomultiplier tube, 21-backscatter extinction trap, 22-integral scattering extinction trap, 23-backscatter measurement frame, 24-optical table , 25-integral measuring frame.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

Referring to Fig. 1 , a kind of comprehensive measuring device of low-loss laser parameter of high reflection mirror, comprises the light source component that is arranged on the optical platform 24, integrating sphere 15, transmission measurement component A, integral scattering measurement component B and backscatter measurement component C, in A photomultiplier tube 20 is arranged on the integrating sphere 15 .

An adjustable optical path deflection device is arranged between the transmission measurement component A and the integrating sphere 15 , and in this embodiment the optical path deflection device includes a movable third reflector 11 and a fourth reflector 12 that are arranged oppositely.

The light source component is a conventional component with a wave plate 4 and an attenuation plate 6, as long as it can provide the required polarization state, suitable light spot and suitable energy, any component can be used. The light source assembly used in the present invention includes a laser light source 1 arranged on an optical platform 24, a polarizer 2, an optical modulator 3, a wave plate 4 (multiple ones arranged on a wave plate fixed disk), a first reflector 5. Attenuation sheets 6 (multiple attenuation sheet fixed disks), beam shaping components 7, and second reflectors 8 . In the forward direction of the light beam emitted by the laser light source 1, a polarizer 2, an optical modulator 3, and an electronically controlled rotating wave plate group 4 are sequentially installed. After the electronically controlled rotation of the attenuation sheet group 6 and the beam shaping component 7, the optical path is turned by 90° through the second reflector 8, which is used as the incident light for measurement.

There are three wave plates 4 and attenuation plates 6 respectively, and they are respectively arranged on the rotatable wave plate fixed disc and the attenuation plate fixed disc. The wave plate fixed disk and the attenuation plate fixed disk are respectively opened with four holes symmetrically distributed at 90° and the centers are located on the same circumference. The three holes on the wave plate fixed disk are respectively equipped with two 1/2 wave plate and a 1/4 wave plate, the other is a through hole, the position of the attenuation plate fixed disc relative to the 1/2 wave plate and 1/4 wave plate on the wave plate fixed disc is set to 1%, 01% and a 0.01% light attenuating sheet, and the other is a through hole.

Said transmission measurement component A is arranged on the optical path of the incident light, including a transmission measurement frame 9 and a transmission extinction trap 10, wherein the transmission extinction trap 10 can adjust its position according to the angle of the incident light, and is arranged on the reflected light path to absorb the reflected light;

Said backscatter measurement assembly B comprises a backscatter diaphragm 13, a backscatter measurement frame 23 and a backscatter extinction trap 21, and a backscatter entrance and a backscatter entrance are arranged on the wall of the integrating sphere 15 on the incident light path passing through the center of the sphere. The backscatter measurement port 18, the backscatter aperture 13 is arranged on the backscatter incident port, the backscatter measurement frame 23 is arranged outside the backscatter measurement port 18, the backscatter measurement frame 23 can rotate, and a backscatter measurement frame 23 is arranged on the optical path of the reflected light. Scattering extinction trap 21;

Said integral scatter measurement assembly C comprises integral scatter aperture 14, integral scatter measurement rack 25 and integral scatter extinction trap 22, integral scatter entrance and integral scatter measurement port are arranged on the wall of integrating sphere 15 on the incident light path, The integral scatter aperture 14 is arranged on the integral scatter incident port, the integral scatter measurement rack 25 is arranged on the integral scatter measurement port, and the integrating sphere 15 wall on the reflected light path between the integral scatter measurement port and the integral scatter extinction trap 22 is provided with an integral Scattering light outlet 16, the optical path of the incident light entering the integral scattering entrance in the integrating sphere 15 is approximately equal to the optical path of the reflected light reflected from the integrating sphere, and the incident angle is the measurement angle, which is 45 degrees in this embodiment.

Accessories are provided on the above-mentioned multiple entrances, measurement ports and light exit ports, and the accessories are standard whiteboards.

The transmission measurement frame 9, the integral measurement frame 25 and the backscatter measurement frame 23 mentioned above are all composed of an electric control turntable and an electric control x-y translation platform, and a fixed ring is arranged on the translation platform. The fixing ring is used to install the sample to be measured.

During measurement, set the measured reflector (sample) on one of the measurement frames involved in the measurement, and the entrance, measurement port, and light exit of other measurement components on the integrating sphere 15 that do not participate in the measurement are all blocked with accessories—standard white boards.

The use principle of the present invention is described in detail as follows:

1. Measuring reference light:

The fourth reflector 12 is removed, and the backscattering entrance, the integral scatter measurement opening, the backscatter measurement opening 18 and the integral scatter light exit 16 are blocked with a standard white board.

The incident light after passing through the transmission measurement component passes through the integral scattering diaphragm 14 and then enters the integrating sphere 15 from the integral scattering entrance. The computer controls the electronically controlled rotating wave plate group 4 to select the required laser polarization state, and the computer controls the electronically controlled rotating attenuation. Sheet group 6 makes the light attenuate by 1%, 0.1% and 0.01% respectively, and converts it into an electrical signal through the photomultiplier tube 20 installed on the integrating sphere, and sends it to the lock-in amplifier for denoising, and then sends it to the computer for processing respectively, as the corresponding reference light Measurements.

2. Measuring the integral scattering rate of the high reflector:

The measured sample 17 to be measured by the integral scattering measurement is set on the integral scattering measurement frame 25, the measured sample is tangent to the integrating sphere, the fourth reflector 12 is removed, and the backscattering entrance and the backscattering measurement opening are blocked with a standard white board 18.

The incident light passing through the transmission measurement frame 9 passes through the integral scattering aperture 14 and then enters the integrating sphere 15 through the integral scattering entrance. On the sample 17 , the reflected light of the sample passes through the integrating sphere 15 and is absorbed by the integrating scattering extinction trap 22 . The integrated scattered light is collected and homogenized by the integrating sphere 15, and then converted into an electrical signal by the photomultiplier tube 20 installed on the integrating sphere, sent to a lock-in amplifier for denoising, and then sent to a computer for processing, and the integrated scattering rate of the high reflector is calculated. The computer controls the electronically controlled rotating wave plate group 4 to select the required laser polarization state, the computer controls the electronically controlled rotating attenuating plate group 6 to rotate to select the appropriate attenuation multiple, and the computer controls the translation of the measured sample 17 to obtain the integral scattering rate of the high reflector 2D distribution plot. It is also possible to measure only the integrated scattering rate of a single point of a high reflective mirror according to the measurement requirements.

3. Measure the transmittance of low transmittance samples:

Remove the fourth reflector 12, and block the backscatter entrance, the integral scatter measurement opening, the back scatter measurement opening 18 and the integral scatter exit light opening 16 with a standard white board.

On the transmission measurement frame 9 of the transmission measurement assembly A, install the sample to be measured—a low transmission sample. The computer controls the rotation of the wave plate group to select the appropriate wave plate 4 to obtain the required laser polarization state, the computer controls the rotation of the attenuation plate group to select the appropriate attenuation plate 6 to obtain the required attenuation multiple, and the computer controls the translation and Rotate the angle to obtain the two-dimensional distribution map of the transmittance of the low transmittance sample of the high reflector at a certain rotation angle. The low transmittance sample to be measured can not only move in plane but also rotate in space on its mounting device, so users can flexibly set the incident angle to obtain the required measurement value. It is also possible to measure only the low transmittance of a single point of a high reflective mirror according to the measurement requirements.

4. Measuring the backscattering rate of high reflectors:

Set the backscatter measurement sample 19 on the backscatter measurement stand 23 , and block the integral scatter entrance, the integral scatter measurement opening and the integral scatter light exit 16 with a standard white board (accessory). The incident light passing through the transmission measuring frame 9 hits the fourth reflector 12 and is reflected on the third reflector 11, and then reflected by the third reflector 11, and the incident light is backscattered after two 90° turnings After the diaphragm 13, it enters the integrating sphere 15 from the backscattering entrance, passes through the center of the integrating sphere 15, and exits from the backscattering measurement opening 18 to the backscattering measurement sample 19, and the reflected light is absorbed by the integral scattering extinction trap 21. The backscattered light is collected and homogenized by the integrating sphere 15 through the solid angle of a small hole, and then converted into an electrical signal by the photomultiplier tube 20 installed on the integrating sphere, sent to the lock-in amplifier for denoising, and then sent to the computer for processing, and the calculation of the high reflection mirror Backscatter rate. The computer controls the electronically controlled rotating wave plate group 4 to select the required laser polarization state, the computer controls the electronically controlled rotating attenuating plate group 6 to select a suitable attenuation multiple, and the computer controls the electronically controlled backscattering measurement frame 19 to translate. Obtain the two-dimensional distribution map of the backscattering rate of the high reflector. It is also possible to measure only the backscattering rate of a single point of the high reflector according to the measurement requirements.

5. When measuring the integral scattering rate, transmittance, and backscattering rate of high reflectors in unknown ranges:

The fixed disk of the attenuation plate can be manually rotated or electrically controlled to make it rotate. Set the light attenuation multiples in the order of 0.01%, 0.1%, 1% and through holes, measure the corresponding values, determine the most reasonable attenuation multiples, and calculate the integral scattering rate, Transmittance or backscatter.

The device measures the laser integral scattering rate, transmittance or backscattering rate of high reflective mirrors in a class 100 ultra-clean and dark room environment.

In the present invention, after the incident light passes through the transmission measurement component, it can enter the integrating sphere in two ways to meet different measurement requirements:

One: Without the fourth reflector, the light can directly enter the integrating sphere, and enter the measured sample tangent to the integrating sphere at a fixed angle of 45° according to the set measurement angle---on the high reflector, on the high reflector The reflected light passes through the integrating sphere and is absorbed by the extinction trap. The opening position of the integrating sphere on the integrating sphere ensures that the integrating sphere is tangent to the electronically controlled integrating scatter measuring frame, and at the same time makes the optical path of the incident light and the outgoing light in the integrating sphere approximately equal .

Second: According to the measurement requirements, the incident light can also pass through the fourth reflector and the third reflector for two 90° optical path transitions, then enter the integrating sphere through the diaphragm, and then backscatter from the center of the integrating sphere (offset is allowed). The measurement opening emits onto the backscattering measurement sample, and the reflected light is absorbed by the integral scattering extinction trap.

The measured scattered light or transmitted light is collected and homogenized by the integrating sphere, and then converted into electrical signals by the photomultiplier tube installed on the integrating sphere, sent to the lock-in amplifier for denoising, and then sent to the computer for processing.

the

Claims (6)

1. A high reflective mirror laser low loss parameter comprehensive measurement device, including a light source assembly and an integrating sphere (15) arranged on an optical table (24), the light source assembly is provided with a wave plate (4) and an attenuation plate ( 6), the integrating sphere (15) is provided with a photomultiplier tube (20), which is characterized in that: it also includes a transmission measurement component A, an integral scattering measurement component B and a backscattering measurement component C; the transmission measurement component A is set at the incident The optical path of the light includes a transmission measurement frame 9 and a transmission extinction trap (10), wherein the transmission extinction trap (10) can adjust its position according to the angle of the incident light, and is arranged on the reflected light path to absorb reflected light; the backscatter measurement component B It includes a backscattering diaphragm (13), a backscattering measuring frame (23) and a backscattering extinction trap (21), and the wall of the integrating sphere (15) is provided with a backscattering entrance and The backscatter measurement port (18), the backscatter aperture (13) is set on the backscatter entrance, and the backscatter measurement frame (23) is arranged outside the backscatter measurement port (18), the backscatter measurement frame (23) can be rotated , a backscatter extinction trap (21) is set on the optical path of the reflected light; the integral scatter measurement component C includes an integral scatter aperture (14), an integral scatter measurement frame (25) and an integral scatter extinction trap (22), in The integrating sphere (15) on the incident light path is provided with an integral scattering entrance and an integral scattering measurement opening, the integral scattering diaphragm (14) is set on the integral scattering entrance, and the integral scattering measurement frame (25) is set on the integral scattering measurement On the port, an integral scattering light outlet (16) is provided on the wall of the integrating sphere (15) on the reflection light path between the integral scattering measurement port and the integral scattering extinction trap (22), and the integral scattering incident light enters into the integrating sphere (15). The incident light at the port is approximately equal to the optical path of the reflected light reflected from the integrating sphere, and the incident angle is the measurement angle; the incident port, the measuring port and the light exit port are all equipped with accessories; the accessories are standard whiteboards. 2. The comprehensive measuring device for high reflective mirror laser low loss parameters according to claim 1, characterized in that: an adjustable optical path turning device is arranged between the transmission measuring component A and the integrating sphere (15). 3. The high-reflective mirror laser low-loss parameter comprehensive measurement device according to claim 1, characterized in that: the optical path turning device includes a movable third reflector (11) and a fourth reflector (12) that are arranged oppositely ). 4. The high reflective mirror laser low-loss parameter comprehensive measurement device according to claim 1 or 3, characterized in that: the wave plate (4) is provided with a plurality, which are respectively arranged on the rotatable wave plate fixed disc Above, there are multiple attenuation sheets (6), which are respectively arranged on the rotatable attenuation sheet fixing discs. 5. The high reflective mirror laser low-loss parameter comprehensive measuring device according to claim 4, characterized in that: the fixed disk of the wave plate is provided with four holes symmetrically distributed at 90° and centered on the same circumference , in which three holes are installed with two 1/2 wave plates and one 1/4 wave plate respectively, and the other is a through hole; the fixed disk of the attenuation plate is opened with 90° symmetrical distribution and the center is located on the same circle The four holes of the wave plate are 1%, 0.1% and 0.01% light attenuation plates at the positions of the 1/2 wave plate and 1/4 wave plate on the wave plate fixed disk, and the other is a through hole. 6. The high reflective mirror laser low-loss parameter comprehensive measurement device according to claim 5, characterized in that: the transmission measurement frame (9), the integral measurement frame (25) and the backscatter measurement frame (23) are all composed of electric The control turntable is composed of an electronically controlled x-y translation platform, and a fixed ring is arranged on the translation platform, and the fixed ring is used to install the sample to be measured.

Images